Root-canal preparing instruments are commercially available for instance in the form of root-canal drill bits, files or rasps and serve to widen and clean root canals.
For that purpose the root-canal preparing instrument with the desired dimensions is selected from a set of such instruments, by manually grasping the desired one by its grip.
The grip of a conventional root-canal preparing instrument is made of solid plastic, such as polyphenylene sulfide, which is resistant to chemicals and heat to facilitate required sterilization after use. Unfortunately, the gripping reliability needed for sure handling is lacking.